First off were Dulce De Leche chocolate brownies (recipe here - http://www.davidlebovitz.com/archives/
I was then forced to eat my words (hah!) when the second cake came out of the oven.
I adapted a classic sponge cake recipe to use the extra dulce de leche I had from the brownies
So, cream together 175g salted butter (straight off the local farm), 175g caster sugar and about 2/3 of a tin of dulce de leche, I'm guessing at about 250g. Make as light and fluffy as you can. Whisk in three eggs 'til even fluffier then fold in 175g of self-raising flour and a teaspoon of pure vanilla essence. Stir until well mixed. Split between two greased cake tins and bake at 170degrees for bout 30mins or until golden and spongy.
Whisk 45g of the butter until fluffy and then whisk in 175g of icing sugar with about two tablespoons of milk (more if needed) til firm and creamy. Spread the buttercream over one cake and sandwich the other on top.
Eat. moan, die a little.